To save cost, space, and energy and labor for operation and maintenance in the entire engine cooling device of a ship.

Pumps 21 including a pump of two-suction port type and a cooler-related devices 51G, 51J are disposed on the lower/upper sides of a passage floor. Pump-related devices are disposed on a side vertical passage girder STR, and all valves are disposed on the front surface thereof. All device-to-device pipes are installed in plant. Composite and on-shelf installation units for supply of cooling seawater-fresh water, cooling and supply of lubricating oil, and cooling of a main machine jacket are configured, and after the units are collectively hanged into the ship, the units are piped and wired to each other or the units are piped and wired to the parts of an engine to be cooled in a single space with a same deck height. An extra power is reduced by the selective operation or flow control of the parallel operation of two pumps with half capacities or different capacities or the independent operations thereof according to the engine output setting for cruising-load handling and the operation of a desalination machine. Also, intake-strainers 3 are collectively disposed, and back-washed together with an outboard intake box 1, back-washable secondary strainers 50G, 50J are disposed in the cooler, and a stationary back-wash is applied thereto so that the engine can be operated and maintained over a long period without overhauling.